Control apparatus



Feb. 25, 1941. R W N 2,232,751

CONTROL APPARATUS Original Filed June 10, 1958 5 Sheets-Sheet l Feb. 25, R. W|LSQN I 2,232,751

CONTROL APPARATUS Original Filed June 10, 1936 5 Sheets-Sheet. 2

I III Feb. 25, 1941. R L w 5 2,232,751

CONTROL APPARATUS Original Filed June 10, 1938 5 Sheets-Sheet 3 Feb. 25, 1941. R. LLWILSON CONTROL APPARATUS Original Filed June 10, 1938 5 Sheets-Sheet 5 Patented Feb. 25, 1941 UNITED STATES REISSUi-ED FEB-101942 PATENT OFFICE CONTROL APPARATUS Original application June 10, 1938, Serial No.

28 Claims.

.This application is a division of my copending application, Serial No. 213,103, filed June 10, 1938.

This invention relates generally to control apparatus, and more; particularly it relates to such apparatus applied to at least two relatively movable elements to detect variation from a desired relative speed of such elements and to accomplish predetermined control operations in response to the detection of such undesired'variation. An instance of two relatively movable elements where such undesired variation in relative speed may occur is found in railway and like equipment wherein the several wheels normally rotate substantially in unison, and wherein material variation from such rotative relation i indicative of an undesired sliding action or tendency toward such an action of one of the wheels.

In the normal operation of railway equipment it is believed that there is no slippage at the points of contact of the wheels of the equipment with the rails and that the wheels roll along the rails. During a braking operation on such equipment the retarding forces effective on the wheels react at the rails to slow down the rolling movement of the wheels and so long as the adhesion between each-wheel and rail on which it rolls exceeds the retarding force effective on the wheel, the wheel is retarded without slippage at the contact thereof with the rail. It has been observed, however, where the retarding force in a braking operation exceeds the force of adhesion between a wheel and the rail on which it rolls, that the wheel slips on the rail and is thereafter retarded at a rate exceeding that at which it would have been retarded had not the slippage occurred and as a result the wheel comes to rest prematurely and thereafter slides along the rail.

There are many factors which may cause the retarding force effective on a wheel in a braking operation to exceed the adhesion between the wheel and the rail on which it rolls. .For example, the braking means of railway equipment is so arranged that the triction between the elements thereof is less than what has come to be generally accepted as the usual value of the adhesion or friction between the wheel or -wheels decelerated by operation of the braking means and the rail or rails on which such wheel or wheels rolls or roll. There may be, however, an unpredictable increase in the friction between the elements of the braking means or the friction betweenthe wheel or wheels and rail or Divided and this application 25, 1939, Serial No. 291,844

August rails may unaccountably drop below what has come to be generally accepted as the value of such friction, and of course there may be a combination of such variations. If such variation occurs in a braking operation it is quite likely that the wheel or wheels affected thereby will slip on, rather than roll on, the rail or rails whereupon, as previously explained, the wheel or wheels may prematurely stop rolling and thereafter slide along the rail or rails. Such sliding of the wheels along the rails may impair the braking operation in which it occurs and may result in serious damage such as producing so-called flats on the wheels. understood that wheel sliding may be occasioned in a wide variety of ways but that however occasioned it is objectionable.

It has been observed in braking operations on railway equipment that, when a wheel slips on the rail on which it normally rolls and prematurely stops rolling and thereupon slides along the rail, the wheel, in so far as its rotative movement is concerned, decelerates rapidly after the slippage occurs and quickly stops rolling to thereupon start to slide and also that where several wheels on differentv axles substantially simultaneously or simultaneously slip on the rail or rails on which they normally roll the wheels usually decelerate, in so far as rotative movement thereof is concerned, at difierent rates and consequently stop rolling and start to slide at different times. Such lack of uniformity in the slowing down of the wheels is probably due to variations in the conditions at the various wheels. These variations in the conditions may be due to differences in the loads on the various wheels on different axles, diflerences in the retarding forces afiecting the respective wheels on difierent axles, or the like. In any event, however, where several wheels on different axles slip on the rail or rails, a variation in the rates of rotation of the various wheels usually arises before any wheel prematurely stops rolling and starts to slide along a rail. I

An important object of the present invention is to detect undesired variation in the relative speed of two or more such relatively movable objects and, in response to such detection, to initiate a control operation such as an operation adapted to restore the desired speed relation.

It is recognized that the rates of movement of the various movable elements, such as the It will be i rates of rotation of the various wheels on a I railway car or the like that are decelerated by independent braking means may not always be the same. For example, as applied to railway equipment, there may be a difference in the diamli eters of such wheels at the lines of contact thereof with the rail or rails which will of course cause the wheels to rotate at different rates in normal operation as well as during a braking operation Thus elements operated at rates proportionate to the rates or rotation of wheels that are decelerated by independent braking means may not always operate at the same rate either in normal operation or during a braking operation. Where such elements are employed to effect a control operation, such as the release of the braking means when the elements operate at different rates during a braking operation, there may be instances where the elements will be operating at different rates even during a. braking operation and yet there will be no need of effecting the control operation because there will not be present an abnormal condition which the control operation is to overcome.

Hence still another object of the present invention is to provide such an apparatus which operates only when the variation in the relative speeds of movement of the several elements exceeds a range predetermined to be indicative of an abnormal or undesired condition.

Since in many instances, as in the case of railway equipment, elements operated at rates proportionate to the rates of rotation of wheels as aforesaid may operate at different rates, as in the course of a braking operation, under condi- 5 tions in which it will not be desirable to effect a control operation, such as the selective releasing of the independent braking means operative to decelerate the respective wheels or sets thereof, it is advantageous to interpose devices entailing a time factor in their operation intermediate the elements and the means under control thereof so that a time factor will enter into the determination of the existence of an abnormal condition and so to do constitutes still another object of the present invention.

More specifically, an object of this invention is to bring about successive or alternate periods of operation of slow-to-release relays and when the intervals between such period of operation are reduced in a predetermined amount to effect simultaneous operation instead of alternate operation, and an object ancillary to the fore-.

going is to render operative means under control of the relays only upon simultaneous operation of such slow-to-release relays.

Further objects are to employ elements, such as may be operated at rates proportionate to the rates of rotation of the wheels of railway or like equipment that are decelerated by independ- 5o ent braking means, to alternately-render operative devices which may be brought into simultaneous operation and thereby bring about a control operation or the likeand to maintain I operative for a predetermined time whatever (:5 means are rendered effective to bring about the control operation whenever the interval intermediate alternate periods of operation of alternately operable devices is so reduced that the intermediate interval is eliminated; and to cffeet concurrent operation of normally alternate- 1y operable devices to bring about a control operation or the like and to maintain operative for a predetermined time whatever means are effective to bring about the control operation only under predetermined conditions.

In an arrangement where devices are alternately set in operation in such a way that under predetermined conditions the interval between the alternate operations is so reduced that the operations become simultaneous rather than 9.1- 5 ternate, it will be recognized that there will be instances where such simultaneous operation may be relatively brief. If such an arrangement is utilized to effect a control operation, such as the release of the braking means employed to de- 10 celerate a particular wheel or set of wheels of railway equipment, conditions might arise where the aforesaid relatively brief simultaneous operations in rather rapid succession might be caused to repeatedly occur for relatively short 15 periods, and this would cause the control or other operation brought about by such simultaneous operations to'be initiated and interrupted, successively, as where the control operation is the release of the braking means for railway 20 equipment operative to slow down a particular wheel or set thereof, it might bring about alternate release and application of such braking means in rather rapid succession. Furthermore, conditions might arise where the aforesaid si- 25 multaneous operation might be brief but should nevertheless effect a relatively prolonged control operation such as relatively prolonged release of the braking means.

Hence, still another object of the present in- 30 vention is to associate with alternately operable devices, which may be brought into simultaneous operation, an arrangement whereby the simul taneous operation'of the devices will be caused to effect a-predeterrnined operationeven though 35 the simultaneous operation may be relatively brief, and an object ancillary to the foregoing is to employ timed apparatus in association with alternately operable devices that may be brought into simultaneous operations so that upon 51- g multaneous operation of the devices a predetermined operation may be effected for at least a predetermined time even though a period of simultaneous operation of the normally alternately operative devices may be relatively brief. 45

In many instances the performance of a control operation tends to reduce the safety factor normally present in the equipment to which it is applied, as in the case of railway equipment where the control operation releases or reduces 50 the effectiveness of the braking means as aforesaid, and in instances of this character it is an object of the invention to provide a detecting and controlling apparatus wherein the control operation is limited to a definite period of time. 5.,

A further object is to provide a detecting and controlling apparatus of this character which may be rendered inoperative manually at any time so as to return the equipment with which it is associated to its normal effectiveness. no

While in the foregoing discussion and in the following detailed description I refer to controlling the braking means of railway equipment, it is to be understood that my invention is not limited to control of the braking means of rail- 05 way equipment for it can be employed to control braking means of other equipment on which slippage of a wheel thereof on the surface on which it normally rolls may occur, and furthermore the fundamentals underlying this inven- 70 tion may be employed to control a wide variety of operations in addition to braking operations. While the invention will be described herein with particular reference to railway equipment, it is capable of still wider application and may be u conveniently and advantageously employed, for example, to maintain a timed relation in the operation of screw propellers on ships, propeller shafts in aircraft applications, machine tool spindles, electrical generator sets, motors used in photographic. transmission, conveyor feeds, and in numerous other instances where moving parts of machinery are correlated. It is therefore to be understood that the foregoing discussion and following detailed description pertain to preferred embodiments of my invention and hence such discussion and description are not to be taken as a limitation of the invention.

Selected embodiments of my novel invention are illustrated in the accompanying drawings wherein I Fig. 1 is a diagrammatic view of one embodiment of my invention associated with a pair of wheels such as are provided at one side of a truck on railway equipment;

. Fig. 2 is a vertical sectional view of a switching means employed in the embodiment of my invention illustrated in Fig. 1;

Fig. 3 is a transverse sectional view taken substantially on the line 33 on Fig. 2;

Fig. 4 is a sectional detail view taken substantially on the line 4-4 on Fig. 2;

Fig. 5 is a view, similar to Fig. 1, showing another form of my invention;

Fig. 6, is a diagrammatic view of a modification of the form of the invention shown in Fig. 5;

Fig. '1 is a diagrammatic view of a still further modified form of the invention shown in- Fig. 5;

Figs. 8 and 9 are diagrammatic views of other forms of my invention; 7

Fig. 10 is a diagrammatic view, partly in elevation and partly in section, of a modified form of switch that may be employed;

Figs. 11, 12 and 13 are still further diagrammatie views of still other forms of my invention;

Fig. 13A is a diagrammatic view of still another form of switch that may be employed;

Fig. 14 is a diagrammatic view of an arrangement providing a common control for a plurality of control devices such as that to which this invention pertains; and a Fig. 14A is a diagrammatic view of a yet further modified form of my invention.

In the embodiment of my invention shown in Figs. 1 to 4, there is a switch S which includes a pair of rotors i5 and [8 respectively fast to shafts l1 and I8 journaled in suitable hearings in the switch housing 19. A gear fast on the shaft 11 meshes with a gear 2| fast on the shaft 22 which is also journaled in suitable hearings in the housing IS, the gears 20 and 2| having a one-to-one ratio. The shaft 22 extends exteriorly of the housing I! and one end of a flexible shaft 23 is connected to this end of this shaft, the other end of the flexible shaft being connected to a gear 24 that meshes with a gear 25 connected to a movable element such as the wheel FW for. rotation therewith. In the present instance flexible shaft being connected to a gear 21 that meshes with a gear 23 connected to a second relatively movable element such as thewheel RW for rotation therewith, this connection of the shaft It to the wheel RW being similar to connection of the shaft 11 to the wheel FW.

The wheels RW and FW as illustrated are to 5 be mounted at one side of a truck (not shown) of railway equipment for movement along the rail T. These wheels are adapted to be slowed down by the usual brake apparatus (not shown) provided on railway equipment, which apparatus includes the brake cylinder C to which a fluid under pressure may be supplied through the pipe P. The brake apparatus is not illustrated inasmuch as the particular construction thereof forms no part of my invention which, in the 15 illustrated forms, pertains to controlling the brake apparatus rather than to such apparatus per se. The relation of my invention to the brake apparatus is apparent from the illustration of my novel control means in association with 20 the brake cylinder C to which fluid under pressure is supplied when the wheels FW and RW are to be slowed down.

In the present instance my novel apparatus is employed to control operation of a solenoid-operated check valve 29 and a solenoid-operated vent valve 30, each of which valves is positioned in the pipe P.

A conductor 32 connects one end of the winding 3| of the solenoid of the valve 29 to one end of the winding 33 of the solenoid of the valve 30. Another conductor 34 leads from the other end of the winding 31 to a source of current such as the battery B. Still another conductor 35 leads from this source of current to a contact 36 of the slow-to-release relay SRI, said contact 36 being engaged by the armature 31 of this relay during operation of the relay. A further conductor 33 leads from the armature 31 to a contact 33 of the slow-to-release relay SR2, this contact 39 being engaged by the armature 400:! the relay SR2 during operation of this relay. Yet another conductor 4| leads from the armature 40 to the end of the winding 33 opposite that to which the conductor 32 is connected. Hence, the windings 3| and 33, the armatures 31 and 40, and the contacts 36 and 33 are connected in series so that energization of the windings 3| and 33 is effected, to thereby operate the valves 23 and 30, only when both the 'armatures 31 and 40 are engaging the contacts 36 and 39, this occurring only when the relays SRI and SR2 are operative simultaneously.

A conductor 42 leads from a source of current such as the battery Bl to a terminal 43. Another conductor 44 leads from the terminal 43 to one end of the winding 45 of the relay SR2 and a conductor 46 leads from the terminal 43 to one end of the winding 41 of the relay SRI. Still another conductor 48 leads from the source of current Bi to a terminal 43, Fig. 2, in the switch S. A further conductor 50 leads from the end of the winding 41 opposite that to which the conductor 46 is connected to a terminal 51 in the switch 8. Yet another conductor 32 leads from the end of the winding 45 opposite that to which the conductor 44 is connected to a terminal 53 in the switch 5.

A conductor ring 54 is mounted on the rotor l-l and a pair of conductor rings 55 and 56 are mounted in spaced relation on the rotor 15. The rotors I3 and it are preferably made of insulating material and hence the conductor rings II and N are insulated one fromthe other. A spring contact I mounted on the terminal 43 bears on the conductor ring 54 while spring conit is believed that there is no slippage at the tacts I8 and 58, respectively mounted on the terminals II and 53, respectively bear on the conductor rings 58 and 5B. A pair of'contact strips '0 and I are mounted in the periphery of the rotor II in diagrammatically opposite positions.

These strips (see Fig. 3) each preierably extend over one-quarter of the periphery of the rotor so that the spacing between adjacent ends thereof is ninety degrees and the extent of each strip over the periphery of the rotor is ninety degrees. A

conductor 62 (Fig. 4) interconnects the contact strip 60 with the conductor ring 5. while a conductor 63 connects the contact strip H with the conductor ring 55. A spring finger 64 is mounted in the rotor IS in electrical connection with the conductor ring 54 and extends over that part of the periphery of the rotor IS on which the contact strips 60 and BI are provided'so that it the rotors I! and I! move relative to each other the spring finger 64 alternatively engages the contact strips and BI. Thus, these contact strips serve as a commutator while the spring finger 64 serves as a brush.

When the spring linger or brush 64 engages the contact strip circuit is established from the source oi current Bl through conductor 48, spring contact 51, conductor ring 54, brush ll, contact strip 80, conductor 62, conductor ring 56, spring contact ll, conductor 50, through winding 41 and conductors l8 and 42 back to the source of current Bl whereupon the slow-to-release relay SR! is energized. When, however, brush 84 engages the contact strip 6| circuit is established from the sourceeoi' current Bl through conductor 48, spring contact 51, conductor ring 54, brush 6, contact strip 6|, conductor 63, conductor ring spring contact ll, conductor 52, through winding 45 back to the source of current Bl through conductors 44 and 42 whereupon the slow-to-release relay SR2 is energized.

It will be noted that the rotor I5 is connected through shaft I1, gears 20 and 21, shaft 22, flexible shaft 23 and gears 24 and 25 to .the wheel W to rotate therewith and in the same direction and also that the rotor I6 is connected through shaft l8, flexible shait 26 and gears 21 and 28 to the wheel RW to rotate therewith and in the same direction. Hence when the wheels F'W and RW are rotating the rotors I5 and I6 rotate at rates proportionate to the rates of rotation oi the respective wheels, and in the present instance, by reason of the one-to-one ratio between the gears of the various sets' thereof, the rotors rotate at the same speed as the wheel to which each is respectively connected. It will be recognized, however, that the rotors could be caused to rotate at greater or less speeds or rates than the wheels. it only being important that the rates of rotation of the rotors be proportionate to the rates of rotation of the wheels.

When the rotors l5 and it both rotate at the same rate there is no relative movement therebetween and the brush 04 rests on one or the other of the contact strips 60 and il or in a space between adjacent ends of these strips, such spaces being of sufllcient width and the brush being sufficiently narrow that the brush cannot engage both contact strips at the same time. Of course, whenever the brush 64 engages one or the other of the contact strips 60 or 6|, either the slowto-release relay SRI or the slow-to-release relay SR! is energized.

In the normal operation of railway equipment points of contact of the wheels with the rails and the wheels roll along the rails. During a braking operation effective on the wheels of such equipment the retarding forces react at the rails to slow down the rolling movement 01 the wheels and so long as the adhesion between each wheel and the rail on which it rolls exceeds the retarding force effective on the wheel, the wheel is retarded without slippage at the contact thereof with the rail. However, when the retarding force in a braking operation exceeds the adhesion between a wheel and the rail on which it normally rolls, the wheel slips on the rail and is thereafter retarded at a rate exceeding that at which it would have been retarded had not the slippage occurred, and as a result the wheel comes to rest prematurely and thereafter slides along the rail.

Thus, where either the rotor It or I6 is connected to a wheel which is retarded in the manner just described and the other rotor is connected to a wheel which continues to roll on the rail, it is apparent that the rotor connected to the wheel which is so retarded will move relative to the other rotor in relatively rapid manner whereupon the contacts or brush 84 will engage. the contact strips BI and Si in rapid succession. The rapidity with which the brush 64 so successively engages the contact strips 80 and 6| is directly proportionate to the magnitude or the difference in the rates of rotation of the wheels. The magnitude of such difference is relatively great when only one of the wheels slips on the rail while the other continues to roll on the rail. However, it has been observed, where several wheels slip on the rails at the same time, that the wheels do not slow down uniformly, this probably being due to varying conditions at the several wheels. Hence, where both the wheels to which the rotors I5 and I8 are respectively connected slip on the rail, it is very unlikely that they will slow down uniformly and hence even in this condition there will be relative movement between the rotors l5 and I6 and the brush 6 will successively engage the contact -strips ill and BI.

As explained heretofore, the contact strips 6| and ii and the contacts or brush 64 are so arranged in circuit with the slow-to-release relays SRI and SR2 that when the brush 64 engages the contact strip or conductor segment 80 the relay SRI is energized, and when :the brush it engages the strip 6| the relay SR2 is energized. Each of these relays is maintained energized so long as the brush 64 remains in engagement with the contact strip in circuit with the particular relay and when, for example, the relay SRI is energized it attracts its armature 31 .which thereupon engages the contact 3. Likewise when relay SR! is energized it attracts its armature ll which thereupon engages the contact 39. Furthermore, each of these relays, being a slow-to release relay, remains operative after circuit thereto is broken, that is to say, for a predetermined time after circuit to the relay is broken its armature remains in engagement with the contact engaged by the armature upon energization of the relay, this being an inherent characteristic of a slow-to-release relay.

Hence, when the brush Gl successively engages the contact strips 60 and Si in such a way that one contact strip is disengaged and the other strip is engaged and the relay in circuit with the second of the strips so engaged is energized in a period of time less than the predetermined time, the relay in circuit with the first of said strips remains operative alter circuit thereto is broken, by disengagement oi the brush 84 from the contact strip in circuit therewith, then both the relays SRI and SR2 are simultaneously operative. When this occursbot-h the armatures 40 and I! v are engaged with their cooperating contacts 39 and 315 and circuit; is closed through the windings 3| and 33 whereupon a control operation, such as release of the braking means effectingretardation or slowing down of the wheels, is effected, as will be more fully explained presently.-

It is recognized that by reason or conditions encountered in the actual use of railway equipment there will be difierences in the rates of rotation of wheels even when all the wheels are normally rolling along. the rails. Such difl'erences in rates of rotation may be due to differences in the diameters of the wheels at the lines of contact thereof with the rails. In fact there may be variations in the diameter or a single -wheel at the line or contact thereof with the rail as the wheel rolls along the rail due to movement of the wheel in an axial direction. Since such conditions will exist, it is apparent that all difierences in rates of rotation between/wheels, to which rotors as I! and I8 are respectively connected, should not cause ,these rotors to so rotate relative to each other that a control operation will be brought about. A control operation is not required unless an abnormal condition exists. To avoid a control operation unless an abnormal condition exists, provision is made to care for an extreme condition in actual-operation, that is, a condition quite unlikely to be encountered, and the apparatus is so arranged that a control operation will not be eil'ected under such extreme condition. In selecting such an extreme condition,-one is chosen that will bracket other similar conditions and improper Jor'undesired effecting of a control operation is therefore avoided.

An example of such an extreme condition is where railway equipment is operating at a speed of one hundred twenty miles per hour and the difference in diameters of the wheels to which the rotors I5 and I5 are connected is one inch at the lines of contact of such wheels with the rail or rails on which they normally roll as, for example, where the diameter of one wheel at the line of contact thereof with the rail is thirty-two inches and the diameter of the other wheel at the line of contact thereof with the rail is thirtythree inches. If a condition such as this .prevailed the rotors I5 and I6 would rotate 'rela tive to each other even in normal operation and in the absence of slippage on the rail for there would be a difierence in rotation therebetween of .634 revolution per second.

'As explained above, each or the contact strips 80 and BI extends over one-fourth of the diamgree interval intermediate adjacent ends or the strips -as well as a ninety degree extent of the strips. Thus, under the foregoing conditions where there is a difference or .634 revolution per second in the rotation of the rotors l5 and IE it will require .394 second for the brush 64 to travel from the end 01 one contact strip 60 or 61 to the adjacent end or'the other contact strip. Hence it the slow-to-release relays are timed to remain operative, after circuit thereto is broken, for less than .394 second,the armatures' 3'1 and 44 will not be simultaneously engaged with their cooperating contacts 36 and 38 under the extreme condition mentioned above which is an operating ,a difference in the diameters of the wheels at the lines of contact with the rail orone inch. It is. however, advantageous to afford a safety factor. Hence the slow-to-release relays may be timed to remain operative after circuit thereto is broken for approximately .242 second. In this circumstance, in order for the armatures 31 and 40 to be simultaneously engaged with their cooperating contacts it is necessary for there to be such relative rotation between the rotors l5 and ii that the brush 64 will move from engagement with one of the contact strips 60 or 6| into engagement with the other of the contact strips in .242 second or less. It will be apparent that this is well beyond the time required for such successive engagement in the extreme condition described above which means th'at a control operation will not be brought about under normal operating conditions.

However, where slippage occurs between a wheel, to which one of the rotors I! or I6 is connected, and the rail on which the wheel rolls, and the other wheel does not slip, or even if there is slippage between both wheels to which the rotors are respectively connected, and the railor rails on which such wheels normally roll, there will be appreciable relative rotation between the rotors l5 and i6. Furthermore, once a wheel slips on the rail it thereafter, so far as its rotative movement is concerned, slows down rapidly and therefore almost or actually simultaneouslystripto the other is equal to or less than .242.

second, both the armatures 31 and 40 will be engaged with their cooperating contacts 36 and 39 whereupon circuit will 'be closed to the windings 3| and 6:! to effect a control operation. Since slippage causes relatively great relative rotation between the rotors 1'5 and It, the brush 94 will move from one contact strip to the other in .242 second or less practically simultaneously with the initiation of wheel slippage. 1

While it is necessary that simultaneous engagement of the armatures Hand 40 with their cooperating contacts is to be avoided in normal operation, it is desirable to establish this simultaneous cooperation promptly under abnormal conditions, as when slippage occurs, and to illustrate the promptitude with which this would be brought about under abnormal conditions it is possible to effect simultaneous closing of the switches, of whichthe armatures 31 and 40 are and I6 for the brush 64 may be near the end of one contact strip at the time rapid relative rotation between the rotors l5 and I8 is initiated and thus the brush need only move slightly more than ninety degrees to engage the other contact strip and cited: simultaneous closing of the switches. It will be recognized that such movement may be effected very rapidly and from this. it will be seen that the device is quite sensitive to abnormal differences in the rates of rotation between wheels as FW and RW.

To further explain the simultaneous closing of the switches, oil which the armatures 31 and 40 are a part, when an abnormal condition arises as, for example. in event of wheel slippage in the course of a braking operation, if the relays SR! and 8R2 have a release time of approximately -242 second and the diameter of both the wheels 5 FW and RW at the lines of contact thereof with the rails is approximately thirty-three inches. (in this circumstance there will beno relative rotation between the rotors II and it in normal operation) a difference in the rates of rotation 10 of the wheels equivalent to approximately six milesper hour-will causethebrush i4 tomove from association with one contact. strip II or II into engagement with the other contact strip in approximately .242 second and in proportionately less time as the difference in the rates of rotation Since it is probable that the rotors I5 and It will be rotating relative to each other even in normal operation, a further example of the op- 20 eration of my novel apparatus. with particular reference to the extreme condition explained above, is now set forth. In such an extreme condition, entailing the connection of the rotors ii and II respectively to wheels having an inch 25 diiference in diameter, that is, where one wheel is approximately thirty-two inches in diameter at the line of contact thereof with the rail and the other wheel is approximately thirty-three inches in diameter at the line of contact thereof 30 with the rail, there will normally be, in the absence of wheel slippage on the rail. a difference of approximately .634 revolution per second in the rates of rotation of the wheels at one hundred twenty miles per hour. This is equivalent to a 8 speed of approximately three and three-quarters miles per hour at the circumference of a thirtythree inch wheel. Now if, in such circumstances, the smaller wheel slips on the rail so as to alter the normal difierence in the rates of rotation so of the wheels, a difference in the rates of rotation between the wheels equivalent to approximately a speed of nine and three-quarters miles per hour at the circumference of a thirty-three inch wheel will cause the brush I4 to move from engage- I ment with one contact strip 80 or ii into engagement with the other contact strip in approximately .242 second and in proportionately less time as the difference in rates of rotation increases.

50 From the foregoing it will be apparent that wherever, the diflerence in the rates of rotation between wheels as W and RW is such that the brush 84 moves from engagement with one con tact strip III or II into engagement .with the 58 other strip in less than .242 second, when the and SR2 have a release time of .242 second. then a control operation is initiated. In the present instance the control operation entails energization of the windings 3|. and I3 with the result that the check valve 28 is closed and the vent valve 30 is opened. In the course of a braking operation fluid under pressure is supplied through the pipe I? to the cylinder C so long as w the check valve 20 is open. Thus when in the course of a braking operation the check valve 20 is closed and vent valve III is opened the cylinder C is disconnected from the source of fluid under pressure by the closing of the valve II and 7 is vented to the atmosphere, in the present instance, by the opening of the valve II, this ventins resulting in reduction of pressure in the cylinder and effecting release of the braking means. Of course the arrangement could be such g" a to reduce the effectiveness of the braking means, rather than release thereof, if this were desired.

As soon as the braking means are released or reduced in eil'ectiveness the retarding force effective on the wheels is removed or reduced, as the case may be, and thereupon the wheels tend to resume normal rolling along the rails. when the wheels resume normal rolling along the rails the difference in the rates of rotation therebetween become such that the brush 84 no longer 10 moves from engagement with one of the contact strips II or ii into engagement with the other of the contact strips in .242 second or less and therefore the switches of which the armatures 31 and 4| are a part do not remain closed with the result that circuit to the windings Ii and II is broken and thereupon the vent valve 30 closes and the check valve 28 opens. If the means operative to bring about the braking operation are still operating when this occurs, the braking means are again rendered effective and if the retarding forces do not again bring about a difierence in the rates of rotation of the wheels there will not be such movement of the brush 84 from engagement with one contact strip Oil or ii into, engagement with the other contact strip that the windings SI and 13 will be energized. If, however, re-application oi' the braking means again sets up a difference in the rates of rotation between the wheels as FW and RW such that the brush 84 moves from engagement with one of the contact strips Oil or ii into engagement with the other strip in .242 second or less, the above described operation will be repeated.

It will be apparent from the foregoing that, since the slow-to-release relays SR! and SR! are simultaneously rendered operative by reason of a difference in the rates of rotation of wheels as W and RW, a control operation can be initiated prior to the time one of the wheels prematurely 40 stops rolling and therefore, where the control operation results in the release of the braking means, sliding of a wheel along a rail may be avoided for when the braking means are released --(or reduced in efiecti-veness) the wheels, being freed ofa retarding force, resume normal rolling along the rail.

In the form of my invention illustrated in Fig. 1 there may be such difference in the rates of rotation of wheels as W and RW that the brush 84 will move from engagement with one contact strip 8! or ii into engagement with the other contact" strip in or less than .242 second to thereby render the relays SRI and SR2 operative simultaneously but the difference in the rates of rotation may be such that the brush it willnot be freed from the second of the contact strips so engaged and move back into ens -s ment with the first of the contact strips soengaged in .242 second. In such an instance the first of the relays SRI or SR2 to be energized might release prior to the time the brush engaged the contact strip in circuit with this particular relay and if this occurred circuit to the windings 3i and 33 would be broken. In a circumstance such as this a condition might arise where the difference in the rates of rotation of the rotors l5 and II would be such that the relays SRI and SR2 might be rendered operative simultaneously as the brush moved from engagement with one of the contact 7 strips 80 or ii into engagement with the other of the contact strips but such simultaneous operativeness of the relays would not be maintained until the brush moved from the second of the t ps 80 engaged backinto engagement with the first of the strips so engaged. It will be apparcut that if conditions such as this arose circuit would be alternately closed and opened through the windings 3| and 33 with the result that the valves 29 and 30 would both be rendered operative and then inoperative, alternately, which is to say, a control operation would be alternately initiated and interrupted.

In order to avoid such alternate initiation and interruption of a control operationmy novel apparatus may be arranged in the manner illustrated in Fig. 5 wherein rotors similar to the rotors i5 and IS in a switch So are respectively connected to wheels Wu. and RWa through flexible shafts 23a and 26a, the switch So and the flexible shafts 23a and 26a being similar to the switch 8 and the flexible shafts 23 and 26 and being adapted for operation in a similar anner. Furthermore, slow-to-release relays S la and SRZa, similar .to relays SR! and SR2, are pro-: vided as well as a source of current as the battery Bla.

In this instance a conductor 42a. leads from the source of current Bla to a terminal 430, and a conductor a leads from the terminal 43a. to one end of the winding 45a of the slow-to-release conductor 48a while a contact strip in the switch I So, corresponding to the contact strip 60 is connected to a conductor 50a which leads to the end of the winding 41a oppositev to that to which the conductor 46a. is connected. Further, a contact strip in the switch Sa, corresponding .to the contact strip BI is connected to a conductor 52a m which leads to the end of the winding a opposite that to which the conductor a is connected. (The switches shown in conductors a and 52a are explained hereinafter and for the purpose of the present description should be con- 45 sidered as being closed.)

Slow-to-release relay SR2a includes an armature 40a and a contact 39a and the slow-to-release relay SRla includes an armature 31a and a contact 36a. A conductor 66 interconnects a 50 contact 39a and the armature 31a. The armature Mia is grounded as indicated at a.

In the form of the invention shown in Fig. 5 a third slow-to-release relay SR3 is provided which includes a winding 61, one end of which is 55 connected to a source of current as the battery B2 through a conductor 68, said source of current being grounded at 89. The other end of said winding 61 is connected to the contact 35a through a conductor I0. The relay SR3 includes an armature H that is grounded as indicated at 12 and this relay also includes a contact 13 1 engageable by the armature 'Il upon energization of the relay SR3.

A solenoid T4 is provided to control operation of the combined check and vent valve 15 provided in the pipe Pa through which fluid under pressure is supplied to the brake cylinder Co which corresponds to the brake cylinder C. Upon energization of the solenoid H the valve 15 is operated to shut off supply of fluid under pressure to the brake cylinder Ca and to vent said cylinder, the valve 15 therefore performing the function of the valves 29 and 30 shown in Fig. 1.

-The solenoid 14 includes a winding 16, one end of which is connected through a conductor 11 to a sourceoi current such as the battery B3 that vis grounded as indicated at 18. A conductor 18 interconnects the other end of the winding 15 to the contact 13. y

In the form of the invention shown in Fig. 5 when a brush in the switch Sa, corresponding to the brush 64, rests on. a contact strip in the switch Sa, corresponding to the contact strip 60, circuit is closed from the source of current Bla through conductor 48a and through the switch S0,, in the manner described in the description of the switch S, to a conductor 50a and through winding 41a and conductors 46a and 42a back to the source of current Bla whereupon the slowto-release relay SRla is energized; When, however, a brush in the switch Sa, corresponding to the brush 64, engages a contact strip in the switch Sa, corresponding to the contact strip GI. circuit is closed from the source of current Bla through conductor 48a and through the switch So, in the manner'described, to conductor 52a and through the winding 45a and conductors a. and 42a back to the source of current Bla where upon the slow-to-release relay SRZa is energized.

Energization of the relay SRia attracts the armature 31a thereof which thereupon engages the contact 36a, this armature remaining in engagement with this contact after circuit to the winding "a is broken for a predetermined time inasmuch as the relay SRia is a slow-to-release relay. Thus the armature 31a engages the contact 36a so long as the relay SRia is operative. Likewise energization of the slow-to-release relay SR2a attracts the armature 40a which thereupon engages the contact 39a, and this armature Illa remains in engagement with this contact after circuit to the winding 45a is broken for a predetermined period of time inasmuch as the relay SR2a is a slow-to-release relay; Hence I0, winding 61, conductor 68, battery B2 to ground 69 to effect energization of the slow-torelease relay SR3. Furthermore, the engagement of the contact 40a with the contact 39a in the absence of the engagement of the armature 31a with the contact 36a likewise does not close the just described circuit to effect energization of the slow-to-release relay SR3.

When, however, a brush in the switch Sa, corresponding to the brush 64, moves from engagement with one of the contact strips in the switch Sa, corresponding to the contact strips 60 and 6|, and engages the other contact strip during the time the slow-to-release relay energized by the engagement of said brush with the first of said contact strips still have the armature thereof engaged with the cooperating contact and the relay energized by engagement of said I slow-to-r'elease relay SR3 energizes.

The slow-to-release relay SR3 has a release time sufllciently prolonged that whenever this I brush with the second of the contact strips has relay is energized it remains operative for a period sufllcient to insure a control operation of not less than a predetermined period of time. Thus where, as in the present instance, the slowto-reelase relay SR3 is arranged to control the supply oi. fluid under pressure to a brake cylinder as Ca, energization of this slow-to-release relay will initiate release of the brakingmeans of which the cylinder Co is a part (or will reduce the efl'ectiveness of such braking means) and will maintain this braking means released (or reduced in eflectiveness) for not less than a predetermined period of time irrespective of how long the armatures, 31a and Ila remain in engagement with their co-operating contacts, this being due to the fact that energization of the slow-to-release relay SR3 initiates an operation which is not interrupted until release of the slow-to-release relay SR3. If the circuit is closed to the winding 31 of the relay SR3 for but a short time the operation under control of the relay SR3 will proceed for a ,period of time equal to the time of relatively brief energization of the winding 31 plus release time of the relay SR3, and since the energization will be relatively brief the control operation will proceed for substantially the period of time represented by the release time of the relay SR3. In any event, however, the control operation will proceed for a period of time equal to the period for which the winding 31 is energized plus the release time oi the relay SR3.

Therefore by providing the relay SR3 with a release time sufficiently prolonged that a control operation of not less than a predetermined period will proceed each time'the relay SR3 is energized it is possible to avoid objectionable alternate initiation and interruption of a control operation such as might result from the utilization of an arrangement such as shown in Fig. 1. Thus where the control operation is the release (or reduction in eflectiveness) of the brakin means of railway equipment, objectionable alternate release and application of the braking means will be avoided. Of course, even in this arrangement alternate release and application of the braking means might occurunder a condition where the winding 31 was only momentarily energized and where, at the expiration of the release time of the relay SR3, both the armatures 31a and a would not be engaging their cooperating contacts, but wherein such engagement of the armatures would be effected shortly after release of the relay SR3 which would again result in energization of the relay SR3 and which would of course bring about another release of the braking means.

Release of the braking means by the arrangement illustrated in Fig. is elected whenever the relay SR3 is operative for when this relay is operative the armature ll thereof is engaged with the contact 13 whereupon circuit is closed from the ground at I2, through armature 1|, contact 13, conductor I3, winding 13, conductor 71, battery B3 to ground at 13, which energizes the solenoid l3 and operates the valve I! o close of! the supply of fluid under pressure to the brake cylinder Ca and vent this cylinder to the atmosphere.

It has been explained heretofore that there may be relative movement between rotors as it and It even in normal operation of railway equipment and it has also been explained that strips 33 and 6! the slow-to-release relay in circuit with the contact strip so engaged by the brush will be energized. However, where my novel apparatus is employed to prevent wheel sliding in the course of a braking operation by either releasing the braking means operative during such a braking operation or reducing the retarding forces established by operation of the braking means, the device may be arranged to prevent energization of the slow-to-release relays except during a braking operation by providing a control device such as the switch 30, Fig. 5. In the present instance the switch 33 is pressure-responsive and is connected to the pipe Pa through a pipe 3| ahead of the valve 15 so that so long as there is fluid under pressure in the pipe Pa (which condition! will prevail so long as a braking peration is in progress) the switch 33 will be closed. The switch 33, as

- shown, may be conveniently arranged in the conductors 33a and 52a to thereby disconnect spring contacts as 53 and 33 from relays as SRIa and SR2a so long as the switch 33 was opened, which condition would prevail until fluid under pressure was supplied through the pipe Pa to the brake cylinder Ca during a braking operation. Hence, the relays as SRla and SR2a could only be energized when abraking operation was in progress which,-in the .present arrangement, is the only time such relays need be energized.

There might also be conditions where it would be desirable to interrupt relative rotation be-' tween rotors as l3 and I3, except when these rotors were to be utilized to effect a control operation, as where the control operation brought about by predetermined operation of the rotors i3 and I6 relative to each other is the release of braking means or the reduction of the retarding force established by operation of such means, the rotors would be rendered operative only when a braking operation is in progress. To this end a fluid-responsive clutch 32 would be interposed between the flexible shaft as 23a and a shaft corresponding to the shaft 22, and another fluidresponsive clutch 33 would be interposed between the flexible shaft as 26a and the shaft as I3. A pipe as 34 connected to the pipe Pa ahead of the valve 13 leads to the clutch 32 through a branch pipe 35 and to the clutch 83 through a branch pipe 36 so that whenever fluid under pressure is supplied to the brake cylinder as Ca through a pipe as Pa the clutches 32 and 83' are engaged to thereby connect a rotor as I5 with a flexible shaft as 23:: and a' rotor as IS with a flexible shaft as 23a.

As will be apparent to those skilled in the art, a switch such as the switch 33 may be employed with or without clutches as 32 and 33 and like- .wise clutches as 32 and 33' could be employed with or without a switch as 33, the use of these devices being dictated by the conditions under v which my novel apparatus is used.

A further modified form of my invention is shown in Fig. 6 and herein a switch so is provided which is similar to the switch S and which includes rotors that in the present instance may be operated at rates proportionate to the rates of rotation of wheels of railway equipment through flexible shafts as'23b and 261) that correspond to the shafts 23 and 23.

A source of current Bib is provided and a conductor 43b leads irom this source of current to a terminal in the switch Sb corresponding to the terminal 39 in the switch S. Conduct tors 33b and 32b respectivelyjlead from terminals in the switch Sb corresponding to the ter minals and 53 in the switch S. The conductor 50b leads to a terminal 81 while the conductor 52b leads to a terminal 88. Three slow-to-realease relays SRIb, SE22) and SR3b are provided.

A conductor 42b leads from the source of current as the battery BIb to a terminal 43b and a conductor 4622 leads from the terminal 43b to one end of the winding 41b of slow-to-release relay SRIb, a conductor 89 connecting the other end of this winding to the terminal 81. A conductor 99 leads from terminal 43b to a terminal 9| and a conductor 44?) leads from the terminal 9| to one end of the winding 45b of the slow-torelease relay SR2b, a conductor 92 leading from the other end of this winding to the terminal 88. A conductor I32 interconnects the armature 311) with the terminal 88. A conductor 93 leads irom.

the contact 881) to a terminal 94. A conductor 95 interconnects the armature 48b with the terminal 81 while a conductor 96 interconnects the contact 39b with the terminal 94. A conductor 'Iub leads from the terminal 94 to one end of the winding 61b of the slow-to-release relay SR3b and a conductor 88b leads from the other end of this winding to the terminal 9I. The armature ill) of the relay SR3b is grounded as indicated at 12b while the contact 131) is connected through a conductor 19b to one end of the winding 16b of a. solenoid 141), the other end of this winding being connected through a conductor 11b to a source of current as the battery 331) which is grounded as at 181).

So long as the slow-to-release relays SRIb, SR2?) and SE31) are operative the armatures 31b, 40b and III) arerespectively engaged with the contacts 36b, 39b and 13b.

In the switch Sb there is a brush similar to the brush 84 and contact strips similar to the contact strips 88 and GI. When this brush engages a contact strip similar to the contact strip 88 circuit is closed from the conductor 48b to the conductor 58?: and when this brush engages a contact strip similar to the contact strip 8| circuit is closed from the conductor 48b to the conductor 52b.

When circuit is closed from the source of current as the battery B"; through conductor 48b, switch Sb, conductor 58b to terminal 81, and through conductor 89, winding 41b and conductors 46b-and 42b back to the source of current Blb, the slow-to-release relay SRIb is energized and the armature 31b thereof is engaged with the contact 86b. In normal operation this does not close circuit to the winding 611: since circuit to the conductor 52b is not closed at the same time circuit to the conductor 5% is closed and therefore the engagement of the armature 31b with the contact 38b does not close circuit from terminal 88 through conductor I32, armature 8117, contact 38b, conductor 93 to terminal 94. While closing of circuit to conductor 581; also closes circuit to conductor 95, circuit is not closed through armature 48b, contact 39b and conductor 96 to terminal 94 unless relay SR2!) is gggrative to engage armature 40b with contact When circuit is closed to conductor 52b, it is also closed to terminal 88 and in normal operation this does not close circuit through conductor I32, armature 31b, contact 3% and conductor 98 to terminal 94 for at this time armature 3*") will be disengaged from contact 361). However. closing of circuit to conductor 52b also closes circuit to conductor 92 and through winding 48b,

conductors 44b, 90 and 42b, circuit is closed back to the source of current Blb whereupon the 'winding 45b of relay SR2b is energized and the armature 48b is engaged with the contact 39b.

In the operation of the device when the brush in the switch Sb corresponding to the brush 84 in the switch S movesirom engagement with,

one contact strip in the switch Sb, similar to the contact strips 88 or 6|, as the case may be, in a period of time such that the slow-to-release relay in circuit with the first of the so engaged strips is still operative at the time the brush engages the other of the contact strips, circuit will be closed to the terminal 94.

Thus, if the slow-to-release relay SRlb were the first of the two relays to be energized and is the one which remains operative, then the armature 31b thereof is engaging the contact 38b wherefore when the brush engages the one of the contact strips that closes circuit to conductor 52b, circuit will be closed from terminal 88 through conductor I32, armature 31b, contact 38b and conductor 93 to terminal 94. At this same time the winding 451) will be energized to engage the armature 402) with the contact 89b and if therefore the brush similar to the brush 64 moves from engagement with the second of the contact strips to be engaged into engagement with the first of the contact strips to be engaged prior to the time the relay SR2b releases, flow of current to the terminal 94 will be established from terminal 81, through conductor 95, armature 4017, contact 39b and conductor 96. I

In either event it will be noted that when both the slow-to-release relays SRIb and SR2b are operative circuit is closed to the terminal 94 from the source of current BIb through conductor 48b and switch Sb and either through conductor 58b, terminal 81, conductor 95, armature 48b, contact 891) and conductor .96 or through conductor 52b, terminal 88, conductor I32, armature 31b, contact 86b and conductor 93.

From terminal 94' circuit is closed through con-.

ductor IIIb, winding 61b and conductors 68b, 98 and 42b back to the source of current Blb whereupon the slow-to-release relay SR3!) is rendered operative to attract its armature IIb into engagement with the contact 13b whereupon circuit is closed through the winding 16b of the solenoid 14b from ground at 121) through armature lib, contact 13b, conductor 19!), winding 18b and conductor 11b to the source of current as the battery B31) and to ground at 18b. This energizes the winding of the solenoid 14b which may be arranged to operate a combined vent and check valve similar to the combined vent and check valve I5, Fig. 5, and thereafter a control operation will proceed in the manner described in connection with the description of Fig.5.

The arrangement shown in Fig. 6 is, quite similar to that shown in Fig. 5 but has an advantage over the arrangement shown in Fig. 5 in that the relay SE31; starts to energize as soon as a brush similar to the brush 84 engages a second contact strip, while. the slow-to-release relay energized by engagement of the brush with the first of the strips is still operative, whereas in the arrangement shown in Fig. 5 it is necessary that the relay in circuit with the second of the strips so engaged be energized before circuit to' slow-to-release relay SR8 is closed. In other respects the arrangements shown in Figs. 5 and 6 operate in an identical manner.

The form of my invention shown in Fig. '7

and indicated by c in Fig. 7 to a terminal corre-v sponding to the terminal ll and in this instance conductor llc would not be connected to a source of current as B as shown in full lines in Fig. 7. Thus in the arrangement shown in Fig. 'l the slow-to-release relay SRlb is energized whenever an abnormal condition exists and the energization of this relay engages the armature IIc with the contact 'Ilc to ground the conductor. Ill.

In the present instance the conductor Ill leads to a terminal 91 and when conductor Ill is grounded circuit, is closed through a conductor ll, armature 99, contact Ill, conductor 19c,

winding Ilc, conductor I'Ic, through the source of current Blc to ground at 180. The winding lie is part of a solenoid Ilc which corresponds to, is for the same purpose II, and operates in the same manner as the solenoids ll and Ilb.

If in the operation of the arrangement shown in Fig. 7 the solenoid 140 is maintained operative for more than a predetermined period of time, then circuit thereto is broken. The predetermined period of time for which the solenoid Ilc may continue to be operative will be of sufllcient length to enable an intended control operation to be completed. Such a control operation, as explained above, may be release of braking means or a reduction in the eflectiveness of such means. When, however, operation oi. the solenoid lie is not interrupted at the end oi such predetermined period oi time, the control operation should nevertheless be interrupted because this will be indicative of an inadvertent and improper condition. To this end a slow-to-energize relay SEI is provided and the aforesaid armature ll and contact Ill are a part of this relay.

The slow-to-energize relay SEI includes a winding "2, one end of which is connected to the terminal 01 through a conductor Ill, the other end of this winding being connected to a source of current as the battery B4 through a conductor Ill, said battery being grounded at Ill. The slow-to-energize relay SEI is such that the armature ll thereof is not attracted from engagement with the contact Ill into engagement with the contact Ill until a predetermined time after circuit to the winding I ll of this relay has been closed by the engagement oi armature IIc with contact Ilc.

Thus when the armature He is engaged with the contact lie to app y ground on the winding Ilc and thereby render the solenoid Ilc operative, circuit is alsoclosed from ground at 12c through armature IIc. contact Ilc, conductor Ill. terminal l1 and thence through conductor Ill, winding Ill and conductor Ill to battery 84 and ground at Ill. This energizes winding Ill but the armature ll of the relay SEI is not attracted until circuit has been closed through the winding Ill for a predetermined time. when, however, circuit remains closed through the winding Ill tor a predetermined period of time, the

armature ll is attracted from engagement with the contact Ill into engagement with the contact Ill and thereupon circuit is closed Irom ground at Ill through the source of current Bl, conductor Ill, winding Ill, conductor I03, terminal lI, conductor ll, armature ll, contact Ill, conductor Ill to fixed contact Ill and through movable contact Ill to ground at I whereby a stick or holding circuit is closed through winding "2 to maintain the relay BEI energized.

Such disengagement of armature 99 from contact Ill breaks circuit to winding Iic wherefore the solenoid 14c is rendered inoperative. The solenoid Ilc willremain inoperative and no further control operations will be eflected until the stick circuit through winding III is broken. This stick circuit can only be broken by manually disengaging the movable contact Ill from the fixed contact Ill and this will not be done until the reason why circuit remained closed to the winding lie for greater than a predetermined period of time has been ascertained. Thus by the arrangement shown in Fig. 'I my device may be rendered inoperative until manually rendered operative and this will occur whenever a control operation is prolonged for greater than a predetermined period oi time.

Obviously it will be advantageous to indicate the disengagement oi the armature 99 from the contact Ill and the engagement thereof with the contact Ill. Hence the slow-to-release energize relay ,SEI is provided with another armature III that is adapted to engage the contact II! simultaneously with the engagement of the armature ll with the contact I". The armature III is grounded as indicated at Ill and a conductor IIl leads from the contact III to a terminal Ill. Thus circuit-is closed to terminal Ill each time a stick circuit is closed for relay SE I A circuit from ground is closed from the terminal III through conductor Ill, a visible signal such as the lamp L and conductor III to a source of current as the battery B5 each time terminal I II is grounded by the engagement of armature III with contact I I2, said source 0! current B! being grounded at I. A conductor Ill leads from the terminal III to an audible signal such as the buzzer N which is connected to a source of current as the battery Bl through a conductor Ill, said battery being grounded as indicated at Ill. Thus the buzzer N is rendered operative each time terminal I II is grounded.

Thus the visible signal L and the audible signal N are rendered operative whenever the solenoid Ilc is rendered inoperative by the disengagement of the armature ll from the contact Ill. While it may be advantageous'to maintain both the audible signal N and the visible signal L operative once circuit thereto is closed, there may be circumstances where it will be desirable to interrupt circuit to one or the other or both of these signals and to this end a manually operable switch may be provided for this purpose, such a switch being indicated at I22 and being provided in the conductor Ill to enable the audible signal N to be rendered inoperative by the manual opening of this switch. 0! course, a similar switch could be provided in the conductor Ill to render the visible signal L inoperative or such a switch could be provided in the conductor IIl so that both of the signals could be tendered inoperative if desired.

The arrangement shown in Fig. 8 is similar to that shown in Fig. 6 except that the arrangement shown in Fig. 8 enables a single source of current to be utilized and a different type of switch is employed.

The switch shown in Fig. 8 includes a shaft I8d suitably journaled in the switch housing (not shown) and this shaft is to be connected to a flexible shaft or the like corresponding to the flexible shaft 26. A shaft I'Id isv also provided and which is also to be journaled in suitable bearings in the switch housing and a flexible shaft similar to the flexible shaft 23 is to be connected thereto. The flexible shafts used with the shafts IId and I8d, Fig. 8, are to be arranged, for example, to cause these shafts to rotate at rates proportionate to the rates of rotation of, and in the same direction as, different wheels of railway equipment or the like, al-

though these shafts need not necessarily rotatein the same direction as the wheels.

In this switch a conductive disc I23 is mounted on the shaft I8d but insulated therefrom and stationary spring contacts I26 engage this disc. Conductive discs I25 and I26 are mounted on but insulated from the shaft Nd, and stationary contacts I21 and I28 respectively engage the discs I25 and I26. A plate I29 of insulating material is also fast on the shaft IId andcarries contact strips 60d and Ski spaced from each other and of an extent similar to the contact strips 60 and IiI. A spring contact 64d is carried by the bracket I30, fast on the shaft I8d, and this spring contact is adapted to successively engage the strips 60d and Ski in a manner similar to that in which the brush 64 engages the contact strips 60 and GI. connected to the disc I23 through a conductor I3I. The contact strips 60d are connected to the disc I26 through a conductor 62d while the contact strips Bld are connected to the disc I25 through a conductor 63d.

In use the shafts H11 and I8d are operated at rates proportionate to the rates of rotation of different wheels on railway equipment or the like and so long as the relative rotation between these shafts is such that the spring contacts 64d do not disengage one of the contact strips "d or 6Id circuit is closed to the slow-to-release relay SR3d.-

Assuming that the spring contact 64d is engaging contact strip 66d, as shown in Fig. 8, then circuit is closed from the source of current BId through conductor I34 to terminal I33 and from there through conductor 48d to spring contact IN and thence through disc I23, conductor I3I, spring contact 64d, contact strips 66d, conductor 62d, disc I26, spring contacts I23 and conductor 56d to terminal 81d. From terminal I'Id circuit is closed through conductor 33d, winding lId and conductors 46d and 42d back to the source of current Bid whereupon slowto-release relay SRId is rendered operative to engage the armature 31d thereof with contact 36d. This however does not close circuit to the winding 81d of slow-to-release relay SR3d since circuit to conductor 52d is not closed at this time. Cir- The spring contact Old is cuit is also closed from terminal am through conductor 95d to armature "d which however at this time is disengaged from contact 3911 wherefore circuit is not closed to the winding 61d.

If, however, the spring contact 64d moves from engagement with the contact strip 60d into engagement with the contact strip 6Id prior to the time slow-to-release relay SRId has released its armature 31d, then circuit is closed from the source of current BId through conductors I34 and 48d, spring contact I2, disc I23, conductor I3I, spring contactild, contact strip Sld, conductor 63d, disc I25, spring contacts I21 and .conductor 62d to terminal 88d.' From terminal 88d circuit is closed through conductor I32d, armature 31d, contact 36d, conductor 93d to terminal 94d. Circuit is also closed at this time from terminal 68d through conductor 92d, winding 45d and conductors d, 90d and 42d back to the source of cur:- rent Bid wherefore the winding 45d of relay SR2d is energized. If, therefore, the spring 'cortact it moves from engagement with the contact strip 6Id into engagement with the contact strip 60d prior to the time relay SR2d has released its armature 40d, circuit will be closed from terminal 81d (to which circuit will be closed in the manner above described) through conductor 95d, armature 40d, contact 39d and conductor Bid to terminal 94d.

In either event when circuit is closed to terminal 94d, winding SM is energized, current flowing from terminal 9411, through conductor IIId,

winding 61d and conductors 63d, I35, 90d and 42d back to the source of current Bld whereupon slow-to-release relay SR3d is energized.

Slow-to-release relay SR3d is similar to and operates in the same manner as slow-to-reiease relay SR3 and when energized attracts its armature I I :1 into engagement with contact 13d whereupon circuit is closed from the course of current BId through conductor I34, terminal I33, conductor 12d, armature lid, contact 1341, conductor I'Id, winding 16d and conductors 19d, I35, 86d and 4211 back to the source of current BId. This renders solenoid 14d operative and this solenoid operates in themanner above described with reference to solenoid I4 tooperate a valve similar to the-valve I5 for the purpose and in the manner above described.

A modification of the form of the invention shown in Fig. 8 is illustrated in Fig. 10, the difference between Figs. 8 and 10 residing in the form of switch employed.

In the form of the invention shown in Fig. 10. shafts lie and lie are suitably journaled in bearings in the switch housing (not shown) and flexible shafts, corresponding to the flexible shafts 23 and 26, are connected to the shafts He and I8e so that they may be rotated at rates proportionate to the rates of rotation of, and in the same direction as, the wheels of railway equipment or the like although, here again, the shafts need not rotate in the same direction as the wheels. The shaft Ile however carries a substantially cupshaped member I3le of insulating material and contact strips 60c and 6Ie are mounted on the inner periphery of the member Ille, said strips being of a length similar to and being spaced similarly to the contact strips 66 and 6| in the switch S. A conductor 63c connects the strip 6Ie with a disc I25e, similar to the disc I25 and on which the brush I2Ie bears. A conductor 62c interconnects the strip he with a disc I26e, similar to the disc I26 and on which the brush I23e, bears. An annular body I'29e, fast on the shaft He, is dis-' posed within the substantially cup-shaped member llle and carries a brush Ne that is urged outwardly by a spring I36 so that the brush will successively ride over the contact strips lie and Ne upon relative rotation between the shafts He and lle. A conductor llle interconnects the brush e withthe disc lac similar to the disc III, and on which the brush ille bears.

The switch shown in Fig. 10 operates in a manner similar to that hereintofore described and could be used in place of any of the switches thus far described. If this were done, for example in so far as Fig. 8 is concerned, the conductor He would lead to a terminal similar to the terminal I33, Fig. 8, while the conductors We and 52's would respectively lead to terminals corresponding to the terminals "d and "d, Fig. 8. It is obvious that with the switch shown in Fig. 10 connected in this manner it would operate similarly to the switch shown in Fig. 8 to bring about a control operation in the above described manner.

A further modified form of my invention is shown in Fig. 11 and herein a somewhat different circuit and a somewhat different switch are illustrated. The circuit shown could be used with any of the switches thus far described and the switch shown herein could be used with any of rates of rotation of such wheels and in the same direction, if desired.

A cam member III is slidably but non-rotatably mounted on the shaft ll! while a cam member III is fast on the shaft I'll. The cam membeta Ill and Ill have complementary cam surfaces I and Ill and a spring I", disposed about the shaft Ill between the cam member Ill and the collar I fast on this shaft, urges the cam surfaces Ill and MI into cooperating relation. When the cam surfaces are cooperating with each other in the manner shown in Fig. 11 the cam member Ill permitsthe rider I" to assume the position shown wherein the contact "I, controlled by the rider I", engages the contact "1. However. if the cam surfaces move relative to each other so that the high portions of the cam surface I are opposite the high portions of the cam surface Ill, then the cam member I38 engagesthe rider Ill and moves the contact I from engagement with the contact I! into engagement with the contact OI}.

Assuming that the shafts l1! and II! have been rotating at substantially the same rate and that the cam surfaces I and III are cooperating with each other in the manner shown in Fig. 11, then the contact I engages the contact "I and circuit is closed from the source of current Bl! through conductor Ill], terminal III}, conductor 48!, contact I, contact If. oonductor III, to armature "I which at this time will be disengaged from contact 38/ and hence circuit is not closed in this instance to any of the slow-to-release relays SRII, SR2! or 8R3].

When, however, the high portions of the cam surfaces I and ill are cooperating with each other, circuit is closed from the source of current Bl] through conductor Ill], terminal III]. conductor I, contact I, contact If, conductor III to terminal I and from terminal III through conductor l2] and winding I, back through conductors I and III to the source of current Bit whereupon slow-to-release relay SR2] is energized and the armature if is engaged with the contact 35!. This however does not close circuit to the winding 41 ii the high portions of the cam surfaces I40 and I II are still opposite each other.

If, however, the relative rotation between the shafts i1! and III is such that immediately after the high portions of the cam surfaces and I have been aligned with each other the cam surfaces move into relationship shown in Fig. 11,

. then the contact 64 engages the contact Ill and thereupon circuit is closed from the source of current Bif through conductor l34f, terminal "If, conductor 40!, contact I, contact 60!, conductor "f to armature If. If the contact 64] engaged the contact 60f prior to the time the slow-to-release relay 8122 has released the armature 40! from the contact 391, then circuit is closed through conductor 86f, winding "I, and conductors 46/, 80/ and 42] back to the source of current Bl! whereupon slow-to-release relay SRI] is energized and armature 31] thereof is engaged with contact "I.

Hence if the relative rotation between the shafts l1! and l8f continues and the high portions of the cam surfaces I40 and Hi move into alignment with each other prior to the time the slow-to-release relay SR1] has released armature 31! from contact 36!, then circuit is closed to terminal "I in the manner above described and from terminal 88/ through conductor I32], armature 31f, contact 36 conductor 10!, winding "I, and conductors 68!, I35], I01 and I2} back to the source of current Bil whereupon slow-to-release relay SR1, energizes.

It will be apparent from the foregoing description that the arrangement shown in Fig. 11 requires the successive engagement of two slowto-release relays in less time than the release times of such slow-to-release relays in order that the slow-to-release relay SR3 will be operative. Hence this arrangement requires that the need for a control operation be prevalent for a greater period of time than any heretofore described. When, however, the slow-to-release relay SR3] is energized it operates in a manner similar to that described with reference to the slow-torelease relay SR3. Fig. 5, and the solenoid H! is rendered operative to operate a valve similar to the valve 15, Fig. 5, or to bring about any other desired control operation, circuit being closed to the winding Iii of the solenoid Ill so long as slow-to-release relay SR3! is operative from the source of current B If through conductor I34], terminal I33], conductor 12 armature llj, contact Ill, conductor 11!, winding 15/ and back through conductors "f,- llif, 90 and 42] to the source of current Blf.

A still further modified form of switch is shown in Fig. 13A and herein shafts llg'and Ila are provided which are adapted to be operated at rates proportionate to the rates of rotation of wheels of railway equipment or other rotative devices to be controlled, and hence these shafts are similar to corresponding shafts previously described. Three discs I239, I259 and I260 are mounted on the shaft Ila to rotate therewith but these discs are insulated from this shaft.

Brushes m i21 and Illa respectively bear on these discs and conductors 48g, 52g and Ila are respectively connected to these brushes. These conductors correspond to the conductors hereinabove described and numbered ll. 52 and both with and without sumxes. Contact strips strip 6Ig is connected to thedisc I25g by a conductor 639, the contact strip 66g is connected to the disc I26 by a conductor 629, while the flexible plates I29g and I299 are connected to the disc I23g by a conductor I3Ig. A plate I45 is fast on the shaft Hg and carries a pair of rollers I46 and I41, of which roller I46 is successively engageable with plungers I46 and I49 in the disc I50 that is fast on the shaft I8g. The roller I41 is a balance roller to avoid unnecessary vibration in the device.

When the shafts I19 and ,Ijg rotate relative to each other the roller I46 so successively engages the plungers I48 and I49 and forces these plungers inwardly that first the flexible plate I299 is engaged with contact strip 50g and then the plate I299 is engaged with the contact strip 6Ig. when this successive engagement of these flexible plates with the contact strips 60g and 6Ig is such that the engagement occurs at intervals of time equal to or less than the release time of slow-to-release relays in circuit with the conductors 52g and 50g, as above described in connection with conductors numbered 43, 52 and 56, both with and without suffixes, then operation of a solenoid such as the solenoid 141 (or the solenoids 3| and 33) is brought about for the purpose hereinabove described, for it will be recognized that the engagement of the flexible plate I29g with the contact strip 609 closes circuit from conductor 489 to conductor 56g while engagement of the flexible plate I299 with the. contact strip 6Ig closes circuit from conductor 4.8g to conductor 52g.

The arrangement shown in Fig. 13 differs from that hereinabove described inasmuch as only one slow-to-release relay is employed to. determine whether or \not a control operation is to be instituted. Furthermore, a somewhat different type of switch is illustrated in Fig. 13.

The switch shown in Fig. 13 includes shafts I1h and IBh similar to shafts I1 and I6 and which are operated similarly to said shafts I1 and I8 A cam member I38h is fast on the shaft I811, while a disc I39h is fast on'the shaft Hit. The cam member I38h' embodies a cam surface I4Ilh including high and low portions. A rocker I5I is pivotally mounted at I52 on the disc .I39h and includes a rider I53 that is urged into engagement with the cam surface 6h by the action of a spring I54 on a plunger I55, said spring and plunger being mounted in the shaft "It as shown in Fig.'13. A guide I55 is mounted on the disc I38h to insure proper rotation of the rocker I5I with the disc I39h. The plungerI55 includesa stem I51 on which the rider I31h bears.

"When the'rider I53 rides on the high part of the cam surface Oh, the stem I51 acts on the rider I31h to hold the contact 64h in engagement with the contact 66h. When, however, the rider I53 moves onto a low part of the cam surface I4Ilh, the stem I51 so cooperates with the rider I 31h that the contact 6411. engages the contact In the switches shown in Figs. 11 and '13, the contacts 64f and 64h may remain in engagement with one or the other of their two cooperating contacts for relatively protracted periods in normal operation of the device but of course when there is relative rotation between the shafts 1 with one cooperating contact into engagement with the other cooperating contact in a relatively rapid manner for when there is appreciable relative rotation between the shafts as I1! and I8! it is indicative, in the present instance, of a wheel sliding condition and therefore a control operation is to be initiated. Of course, due to sharpness of the inclination between the two different cam surface levels of a device shown in Fig. 13, the shift of contact 64h from either contact 60k. or 6Ih to the other will occur more rapidly than in the arrangement shown in Fig. 11 for the same difierence in the rates of rotation between the shafts. Furthermore, it is intended that by reason of such sharpness of inclination between the cam surfaces the contact 64h will move from either contact 60h or 6Ih to the other, or vice versa, in'such time that there will be little if any interval between such engagements.

In normal operation so long as the contact 64h remains in engagement with the contact 66h circuit is closed from the source of battery BIh through conductor I34h, terminal I33h, conductor 48h, contact 64h, contact 60h, conductor 50h to terminal 8171. This closes circuit to conductor'I58 and winding I59 of slow-to-energize relay SE2 for this complete circuit back to the battery Blh. through conductor I60, terminal I6I, conductor I62, terminal I63 andconductor 42h. Relay SE2 being a slow-to-energize relay may therefore energize in normal operation toattract its armature I64 from normal engagement with the contact I65 but this is without effect in normal operation. Furthermore, when circuit is closed to terminal 81h circuit is also closed to conductor I66 and terminal I69. From terminal I69 circuit is then closed'through conductor 95h to armature I66 which remains dis: engaged from contact I61 until relay RI is energized. Closing of circuit to terminal' I69 closes circuit through conductor I10, winding "I of slow-to-release relay SR4, conductor I12, terminal I13, conductor I14, terminal I 6I, conductor I62, terminal I63 and conductor 4271. back to the source of current BIh. This energizes slow-torel'ease relay SR4 whereupon the armature I 15 thereof is attracted into engagement with contact I16. In normal operation the engagement "of armature I15 with contact I16 is without ef- 60h and-is almost instantaneously moved into engagement with contact Iilh whenever the rider I53 moves from the high portion of the cam surface Oh and onto the low portion thereof. It has also been stated that in normal operation there is apt to be a slight difierence in the rates of rotation of the wheels to which the rotating elements as I38h and I39h of, the switch assembly are respectively connected, due, for example, to a discrepancy in diameters of these wheels. Therefore, it mayhappen'that' in normal operation the contact 6412; will become disengaged from contact sun and will move into engagement with contact 6| h before the slowto-release relay SR4 has been deenergized by the separation of the contacts Silk and 64h. This will complete a circuit from source of current III, as Just described, and thence through contact I'll, conductor I'I'l, terminal Ill, conductor I'll, winding ill of relay RI, conductor IlI, terminal I'll, conductor I'll, terminal Ill, conductor Ill, terminal Ill, and conductor in back to the source of current Bin, whereupon relay RI is energized.

The slow-to-release relay SR4 also includes an armature Ill which remains in engagement with the contact Ill so long as the armature I'll remains in engagement with the contact I'll. Hence at the time circuit is closed through the winding Ill of relay RI, circuit is also closed from battery BIh through conductor Illh, terminal Illh, conductor Ill, terminal Ill, conductor Ill, armature I82, contact Ill, conduc tor Il'l, armature Ill and contact I ll, inasmuch as slow-to-energise relay SE2 is not energized at this time, and through conductor Ill to terminal Ill. Since at this time relay RI i s enersized, circuit is now closed from terminal Ill, through conductor Ill, contact Ill, armature ll! of relay RI through conductor Ill to terminal I'll whereupon a stick or holding circuit for relay RI is established.

As will be shown more fully hereinafter, the emulation of relay RI is without effect upon the remainder of the apparatus unless slow-torelease relay SR4 maintains its armatures I'll and Ill in engagement with their respective contacts I ll and Ill throughout the entire interval between two successive engagements of the contact h with contact llh. During normal operation this interval is always greater than the deenergization time of the relay SRl, so that relay RI will be deenergized, as a result of the disengagement of armatures I'll and Ill from their respective contacts upon deenergization of relay SRI, prior to the time contact llh. again engages contact llh. Hence, during normal operation the armature Ill of relay RI will be disengaged fromits contact I" at all times when contacts llh and It are in engagement with each other, and therefore circuit is not completed beyond armature Ill.

However, when an abnormal condition arises and the shafts "It and Ilh start to rotate relative to each other at such a rate .that after the contact-h has engaged the contact l in and energized the relay RI the contact Mn is caused to engage the contact llh prior to the time the slow-to-release relay SR4 has released its armatures I II and I ll, then circuit is closed from conductor Ill, terminal I", conductor llh, armature Ill of relay RI, which relay will be held energised by the above traced stick circuit, and contact I", conductor Ill, terminal Ill, conductor Ill, winding ill of relay R2, conductor Ill, terminal Ill, conductor Ill, terminal Ill and conductor 42h back to the battery BI, whereupon relay R2 is energized. Furthermore, circuit is closed from the source of current Blh through conductor Illh, terminal Illh, conductor llh, contact llh, contact llh, and conductor Ilh to terminal llh to again initiate energization of slow-to-release relay SE2 through conductor Ill as, above described.

The above described energization of relay R2 closes a stick or holding circuit therefor from terminal Ill throughconduotor Ill, contact Ill,

armature ill of relay R2 which will be englled with contact 28!, upon energization of said relay RI. and through conductorill to terminal Ill,

Blh through contacts h and llh to armature Hence, so long as slow-to-energize relay SE2 does not attract its armature Ill and so long as slowto-release relay SR4 does not release its armature I82, the relays RI and R2 will be held energized. However, upon the energization of slowto-energize relay SE2 or the release of armature Ill of slow-to-release relay SR4, at the end of aperiod of operation of this relay, the stick circuits for the relays RI and R2 are broken and thereupon these relays release.

So long as the relay R2 remains energized the armature I Ih thereof is held in engagement with the contact 13h whereupon circuit is closed through conductor 'l'lh, winding 18h, conductor 'llh, terminal I98, conductor 200, terminal I" and conductor 42h back to the source of current Blh wherefore the winding "It is energized to render the solenoid 14h. operative. Solenoid 'llh is similar to solenoids heretofore described bearing this reference character with or without suffixes and therefore energization of the winding 'llh brings about a control operation as above described.

In Figs. 9 and 12 I have illustrated arrangements wherein switches such as those which have been. thus far described may be supplemented by means for generating an electromotive force upon relative rotation of wheels of railway equipment or the like, such as the relative rotation between such wheels as causes operation of the switches described above.

Thus in Fig. 9 I show shafts Ill and Ill. A bracket Illi is provided on the shaft Ill and carries field pieces FI and F2, and an armature A is fast on the shaft I'li for cooperation with the field pieces FI and P2. ,In Fig. 12 I have diagrammatically illustrated an armature A! and brushes Ill! and II. It will be apparent that upon rotation of the shafts Ill and ill relative to each other that the field pieces FI and F2 will rotate relative to the armature A whereupon electromotive force will be set up in the armature A. Upon similar relative movement between the armature A1 and field pieces corresponding to the field pieces/Fl and F2, Fig. 9, an electromotive force will be generated in the armature Ad.

Referring first to the form of the invention shown in Fig. 9, a switch similar to that shown in Fig 8 is employed, said switch comprising the plate Ill! of insulating material on which contact strips Ill and ill similar to the contact strips lld and lld, Fig. 8, are provided to be successively engaged with the spring contact lli. Then in the manner described with reference to Fig. 8, circuit is alternately closed from the conductor Ill to the conductors ill or 521.

Either in the" manner disclosed in Fig. 8 or in any other suitable way, the conductors-i, Ill and lit will be connected in circuit with devices which will bring about operation of a slow-torelease relay SRli, the slow-to-release relay SRli, for example, corresponding to the slow-to-release relay SRld, Fig. 8. To further illustrate how the slow-to-release relay SR3! could be placed under control of circuits of which-the conductors 48!, Ill and it are a part, conductors Ill and ill are shown connected to oppositeends of the winding ll! of the slow-to-release relay SRli. Such conductors Ill and 88! could lead respectively to terminals as Old and 20!, Fig. 8.

When circuit is closed through the winding 8'" to energize the slow-to-release relay SRli the armature 'Ili is attracted into' engagement with the contact 'lli whereupon circuit is closed from a source of current as the battery 133i through conductor 18:, terminal 206', conductor 12i, armature 1li, contact 131, conductor 191', terminal 201, conductor 208, winding 162' and conductor 11: back to the battery B31 whereupon the solenoid 142' of which the winding 16i is a part is rendered operative to bring about a control operation such as, for example, that brought about upon energization of the solenoid 14d described above.

It will be recognized that energization of the slow-to-release relay S332 is brought about by rotation of the shafts I12 and I81. relative to each other, for example, as relative rotation of the shafts H11 and id; Fig. 8, brings about energization of the slow-to-release relay SR3d. When such relative rotation between the shafts Hi and I81 occurs there is relative rotation between the field pieces Fl and F2 and the armature A whereupon an electromotive force is set up in the armature A. A conductor 209 leads from one end of the winding of the armature A to a conductor disc 2H1 mounted on, but insulated from,

, the shaft |1i while another conductor 2 leads from the other end of said winding to a conductive disc 2l2 mounted on, but insulated from, the shaft I12. A stationary spring contact 213 bears on the disc 2"] and another stationary spring contact 2 bears on the disc 2l2. A conductor 2l5 leads from the spring contact 2l3 to one end of the winding 2l6 of a relay R3 while a conductor 2" leads from the other end ofthe winding M6 to the spring contact 2. 7

Thus an electromotive force set up in the armature A is impressed on the winding H6 and when this electromotive force is of sufllcient magnitude, which would be directly proportionate to the magnitude of the relative rotation between the shafts I12 and ii, relay R3 is energized whereupon the armature 2I8 thereof is attracted into engagement with the contact 2H and thereupon circuit is closed from the source of current as the battery B311 through conductor 181', terminal 205, conductor 2 20, armature 2| 8, contact 2l9, conductor 22!, terminal 201, conductor 208, winding 161', conductor 111', and back to the battery B31- which affords another source of energization for the solenoid Hi. I

It will be apparent, so long as the relative rotation between the shafts I11 and I81 is great enough to generate an electromotive force sufficient to effect operation of the relay R3 that circuit will be closed through the winding 16i wherefore the solenoid 141' will be maintained operative for the purpose above described.

The arrangement including the relay R3 need not be, but could be, as sensitive, or even more sensitive, than that icluding the slow-to-release relay SR3z but preferably is not as sensitive so that once the relay R3 is rendered operative it will bring about and maintain a control operation, such as is brought about by operation of the solenoidHi, so long as an abnormal condition, indicated by rotation of the shafts Hi and I81" relative to each iother, is prevalent. Of course, when the relative rotation between the shafts I11 and I81 is so reduced that the electromotive force set up is not suflicient to maintain the relay R3 energized, the relay releases and thestick circuit for the winding 162' closed by engagement of the armature 2|8 with the contact 219 will be broken. Either before or after this, depending upon conditions, the slow-to-release relay SR3i willrelease freeing the armature Hi from the contact 13: whereupon the circuit closed by engagement of said armature with said contact is opened. If desired, a slow-torelease relay could be used in place of the relay R3.

From the foregoing it will be apparent that the arrangement shown in Fig. 9 is such that a dual source of energization for the winding 161' of the solenoid 142 is provided and hence if one or the other of the means controlling this dual source of energization should fail to operate as intended the other may be relied upon to bring about a control operation.

In Fig. 12 a modification of the arrangement shown in Fig; 9 is illustrated and herein a conductor 2H7 leads from the brush N37 to one end of the winding Zlfia' of the relay R37 while a conductor 2l5a' leads from the other end of this winding to the brush 2H1.

It will be understood that the field pieces of the generator shown in Fig. 12 are arranged for rotation at a speed proportionate to the rate of rotation of a wheel of railway equipment or the like while the armature A7 is arranged for rotation at a rate proportionate to another such wheel and that when the relative rotation between these field pieces and the armature A5 is -winding 167" has another source of energization which is from ground at 121' through armature 1|;i when it is engaged with contact 131 and thence through conductor 197', terminal 224, conductor 225 and circuit is thereupon closed through winding 167', conductor 117', battery B37 to ground at 187'.

The armature 1| is part of a slow-to-release relay SE37, the winding 51; of which is energized from ground at 69 through a source of current as the battery B2 and conductor 689, which is connected to one end of the winding 519'. A conductor 101 is connected to the other end of the winding 617' and may, for example, be led to a suitable point such as the contact 36a, Fig. 5, so that when a ground connection is made to the contact as 36a in the manner described hereinabove the relay SE37 will be energized.

As in the case of the arrangement shown in Fig. 9, the means for generating an electromotive force is intended to supplement the action of a switch which would cause ground to be applied on the winding 617 when an abnormal condition such as predetermined relative rotation between the wheels of railway equipment exists. The two sources of energization for the winding 16 of the solenoid 14 can be used to supplement each other but of course one or the other of such sources of energization could be used alone if so desired.

There may be instances where it will be desirable to render devices under control of switches as S inoperative as where on railway equipment it is desired to make an emergency stop in such circumstances that it is immaterial whether or not the wheels of the railway equipment may slide. It will be apparent from the foregoing description that devices such as those which are under control of the switches as S, or means for 

